‘Invisible’ woven patterns could help detect counterfeit clothing

A researcher in Sweden has produced a thread with unique optical properties that can be used to create invisible patterns in fabrics that are only visible under polarised light.

According to Swedish Customs, trade in counterfeit and pirated goods has exploded the past few years in Sweden, the EU and globally. The situation impacts companies, their employees and consumers and it is often difficult to spot the difference between a genuine garment and one that isn’t.

Christian Müller, a researcher in polymer technology at Chalmers University of Technology, has created a partially invisible thread made of polyethylene and a dye molecule that absorbs visible light.

The thread – which is said to be easy and inexpensive for a company to produce – can be weaved into a pattern that is invisible to the naked eye, but which can be seen using a polarisation filter.

‘The production process itself uncomplicated,’ Müller said in a statement. ‘Clothing manufacturers could start using the thread right away to put a signature pattern in their garments. The equipment needed to see the pattern is fairly simple, and is already in place at Swedish Customs, for example.’

The invisible thread can be created using several different dye molecules and several different synthetic fibre textiles and natural fibres such as wool and silk. The idea is for a brand to be associated with its own special combination of textile fibres and dye molecules.

Müller said, ‘It is very difficult for pirate manufacturers to copy the unique combination.

‘They can obtain the equipment needed to read the pattern and ascertain the optical spectrum produced by a specific signature, but they cannot know which combination of components will produce the specific spectrum.

‘And there are loads of different dye molecules available for use.’

Using invisible thread can help clothing manufacturers create a logotype that is part of the actual fabric and that only becomes visible under polarized light. The technology produces a specific optical spectrum that is very difficult for pirate manufactu
Using invisible thread can help clothing manufacturers create a logotype that is part of the actual fabric and that only becomes visible under polarized light. The technology produces a specific optical spectrum that is very difficult for pirate manufacturers to copy